B2: Organisation Flashcards
What is a tissue?
Groups of cells that have similar structures and functions
What is an organ?
A group of tissues working together to perform a specific function
What is an organ system?
Groups of organs working together
What is the order of the digestive system and each part’s function?
- Teeth; break down food mechanically; saliva contains amylase
- Oesophagus; food travels down
- Stomach; contains hydrochloric acid & enzymes that chemically break down food
- Liver; produces bile, stored in gall bladder before going into small intestine
- Pancreas; secretes amylase which breaks down starch into glucose in the small intestine
What is the function of bile?
- Neutralise stomach acid
- Emulsify lipids to form droplets, increasing their surface area
How are nutrients absorbed into the bloodstream?
Via villi in the small intestine
How is water absorbed into the bloodstream?
Via the large intestine
What are enzymes?
Biological catalysts
Proteins
Often break down molecules into shorter ones
What does amylase break down and what is the product?
Breaks down starch into glucose
What does protease break down and what is the product?
Breaks down proteins into amino acids
What does lipase break down and what is the product?
Breaks down fats into fatty acids and glycerol
How do enzymes work (lock and key theory)?
- The enzyme’s active site is a specific shape
- The enzyme will only catalyse a specific reaction because the substrate fits into its active site
- At the active site, enzymes can break molecules down into smaller ones or bind small molecules together to form larger ones
- When the products have been released, the enzyme’s active site can accept another substrate molecule
How does temperature affect enzyme activity?
Activity increases with temperature until the optimum temperature is reached and then the enzyme starts to denatures when it gets too hot
What happens when an enzyme denatures?
The active site changes shape
How does pH affect enzyme activity?
Activity increases until optimum pH and then decreases
What is the enzyme practical for starch?
- Mix amylase with starch and start timer
- Remove a few drops from mixture every 10 seconds and add to iodine
- Record the time taken for no starch to be detected (will remain orange)
- Repeat at different temperatures or with different pH buffer solutions added
- Optimum pH/temp is between two lowest times
What is the food test for starch?
Turns iodine from orange to black when starch is present
What is the food test for sugars?
Turns 10 drops Benedict’s solution from blue to orange when sugar is present
Must be heated in a water bath of 95 degrees celcius for five minutes
On a scale - green = small amount of sugar, brick red = large amount of sugar
Only works with reducing sugars such as glucose
What is the food test for protein?
2cm^3 food solution and 2cm^3 biuret solution
Turns biuret’s reagent from blue to purple when protein is present
What is the food test for lipids (fats)?
Grind food with distilled water using mortar and pestle but do not filter
Add few drops of distilled water and ethanol
Gently shake solution
Turns cold ethanol cloudy when lipids (fats) are present
Where does air travel through the respiratory system?
- Trachea
- Bronchi
- Bronchioles
- Alveoli
What are features of the alveoli to maximise gas exchange?
- Large surface area
- Lots of capillaries (good blood supply)
- Moist
- Thin walls
How does oxygen diffuse into the bloodstream?
- Diffuses into bloodstream through alveoli
- Binds to the haemoglobin in red blood cells to be transported
What is dissolved into the plasma of the blood and then exhaled?
Carbon dioxide
What is a double circulatory system?
Blood enters the heart twice every time it is pumped round the body
Where does deoxygenated blood enter?
The right side through the vena cava
What are valves in the heart used for?
To prevent backflow
Where does blood go after the vena cava?
Right atrium
Where does blood go after the right atrium?
Right ventricle
Where does deoxygenated blood exit the heart?
The right side through the pulmonary vein
Where does blood go after exiting the pulmonary vein?
To the lungs to be oxygenated
Where does oxygenated blood enter?
The left side through the pulmonary vein
Where does blood go after the pulmonary vein?
Left atrium
Where does blood go after the left atrium?
Left ventricle
Where does oxygenated blood exit the heart?
The left side through the aorta?
Where does blood go after exiting the aorta?
The rest of the body
What are pacemaker cells and where are they located?
A group of cells near the right atrium that creates an electrical pulse that causes the heart to contact
Which side of the heart has thicker walls and why?
- Left side
- Higher pressure needed to pump blood to the body
What can be used if pacemaker cells aren’t working correctly?
An artificial pacemaker
What are features of arteries?
- Always go away from the heart
- Thick walls
- Thin lumen
- Stretch and withstand high pressure
What are features of veins?
- Always carry blood towards the heart
- Thin walls
- Wide lumen
- Valves to prevent backflow
- Lower blood pressure
What can be used if valves are faulty?
Artificial valves
What are features of capillaries?
- One cell thick walls
- Fast diffusion between blood and cells because of short diffusion distance
- Very narrow lumen
What is coronary heart disease (CHD)?
When the artery supplying blood to the heart becomes blocked by the build up of fatty acids
How does fat cause CVD (cardio-vascular disease)?
Fat builds up and restricts blood flow
What are 2 ways to help treat the build up of fat in blood vessels?
- Stents - inserted to open up the vessel
- Statins - drugs that can reduce fatty acids
What are the components of the blood?
- Red blood cells
- White blood cells
- Platelets
- Plasma
What is a communicable disease?
One that is caused by a pathogen so can be transferred between people
What is a non-communicable disease?
Cause comes from inside the body so cannot be transferred between people
What can cause type 2 diabetes?
Obesity & poor diet
What can cause heart diseases?
Poor diet, smoking & lack of exercise
What can cause liver disease?
Alcohol
What can cause lung cancer?
Smoking
What is a carcinogen?
Anything that can increase the risk of cancer
What is cancer?
An auto-immune condition resulting from genetic mutation causing cells to multiply uncontrollably - tumour
What does benign mean?
Does not spread
What does malignant mean?
Spreads through body
What happens within the leaf?
- Photosynthesis, gas exchange
- Water evaporates out
What is the function of the xylem?
- Continuous tubes that carry water & dissolved mineral ions upwards to leaves
- Transpiration (unidirectional) rate increased with increased air movement (wind removes water vapour quickly, maintaining steeper concentration gradient) or temperature (water evaporates faster)
- Transpiration decreased with humidity (shallower concentration gradient)
- Light intensity increases rate of transpiration (stomata open wider to let more carbon dioxide into the leaf for photosynthesis)
- Provides water to cells to keep them turgid
- Provides water for photosynthesis
- One way transport only
- Made of dead cells
- Thick walls stiffened with lignin
What is the function of the roots?
- Water enters through osmosis
- Mineral ions enter through active transport
- Increased absorption of water and mineral ions into the root by increasing the root surface area
- Contain lots of mitochondria to transfer energy, which is used to take in mineral ions by active transport
What happens in the meristem?
Stem cell production
What are in the flower?
Reproductive organs
What is the phloem?
- Tubes of cells that carry sugars (e.g. sucrose) and other nutrients where needed from the leaves to the rest of the plant
- Translocation - bidirectional
- Allows for respiration, growth and glucose storage
- Cells have end walls with small holes to allow substances to flow through
What happens when there is a lack of nitrate ions?
- The plant can’t carry out protein synthesis
- This leads to stunted growth
What is chlorosis and what happens?
- Magnesium deficiency
- Yellow leaves and stunted growth as there is less chlorophyll
What is the function of the waxy cuticle?
Waterproof to stop water loss from the top of the leaf via evaporation
What is the function of the upper epidermis?
Transparent to let light through
What takes place in the palisade mesophyll layer?
Photosynthesis
What is the function of the spongey mesophyll?
Gaps to facilitate gas exchange (large surface area)
What does the vascular bundle contain?
The xylem and phloem
What is the lower epidermis?
The bottom of the leaf
What are stomata?
Holes in the lower epidermis to allow gases in/out, including water
Lots of water = turgid, cell wall very thick so cannot stretch as much as the outer surface so swells up and curve away from each other, opening stomata
What is the function of the guard cells?
To control the size of the stomata to control the rate of gases entering & exiting through
What is the structure of a leaf?
- Waxy cuticle
- Upper epidermis
- Palisade mesophyll
- Spongey mesophyll
- Vascular bundle
- Lower epidermis
- Stomata
- Guard cells
What is an organism?
Organ systems work together, forming an organism
What is the function of red blood cells?
To bind to oxygen and transport it around the body
What is the function of plasma?
Transports substances and blood cells around the body
What is the function of platelets?
Form blood clots to create barriers to infection
What is the function of white blood cells?
Part of the immune system to defend the body against pathogens
Where is amylase found?
- Salivary glands - produced
- Pancreas - produced
- Small intestine
Where is lipase found?
- Produced in pancreas
- Small intestine
Where is protease found?
- Stomach
- Small intestine
- Produced in pancreas
What is the optimum pH for protease?
2
What is the optimum pH for amylase?
7
